to_ruby is a really convenient way to compare the equality of two lambdas. It’s a bit slow though. If we get our hands dirty (only a little!) with ParseTree, we can get a result 2 orders of magnitude quicker. I’d be interested to see if these benchmarks differ significantly on other versions of ruby.
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~ $ ruby -v
ruby 1.8.6 (2007-09-23 patchlevel 110) [i686-darwin8.11.1]
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require 'benchmark'
require 'parse_tree'
require 'ruby2ruby'
def gen_lambda
lambda {|x| x + 1 }
end
Parser = ParseTree.new(false)
# This only requires parse tree, not ruby2ruby
def proc_identity(block)
klass = Class.new
name = "myproc"
klass.send(:define_method, name, &block)
# .last ignores the method name and definition - they're irrelevant
Parser.parse_tree_for_method(klass, name).last
end
n = 1000
Benchmark.bmbm do |x|
x.report("#to_ruby") { n.times { gen_lambda.to_ruby == gen_lambda.to_ruby }}
x.report("#to_sexp") { n.times { gen_lambda.to_sexp == gen_lambda.to_sexp }}
x.report("manual") { n.times { proc_identity(gen_lambda) == proc_identity(gen_lambda) }}
end
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user system total real
#to_ruby 4.460000 0.220000 4.680000 ( 4.695327)
#to_sexp 0.920000 0.190000 1.110000 ( 1.110214)
manual 0.030000 0.000000 0.030000 ( 0.032768)
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In case you were wondering, I was playing around with this while implementing unique data generation for dm-sweatshop
